1. Field of the Invention
The present invention pertains to telecommunications, and particularly to a telecommunications exchange.
2. Related Art and other Considerations
Subscribers to telecommunications services are connected to one another through one or more networks so that a connection, e.g., a telephone call or data transmission, for example, can be made between the subscribers. The networks including various nodes or exchanges through which the connection is routed. In this regard each subscriber is connected by land lines to a local exchange, with local exchanges being connected together when necessary (via land lines) by one or more transit exchanges. Each local exchange and transit exchange typically has a large and complex switch through which connections are routed between incoming and outgoing lines.
One example of a traditional switch utilized for telephone exchanges is known as the group switch, such as the AXE Group Switch of Telefonaktiebolaget L. M. Ericsson. A group switch typically includes both space switch modules and time switch modules in a switch core, as well as group switch software. The entire exchange including the group switch is under the control of a central processor and plural regional processors. The central processor and regional processors execute the group switch software as well as other software for the exchange. The group switch further has special hardware for forming connections to line switch modules for handling traffic and signaling. The line switch modules are ultimately connected outside of the exchange, e.g., to the subscribers Even the smallest group switch generally can handle several thousand connections.
Telephone exchanges which include group switches are complex and expensive. The complexity and expense result at least in part from dedicated hardware components employed in the exchange, as well from the size of the group switch itself. In addition, the central processor is a customized processor which is considerably more expensive than industry standard processors.
Since telephone exchanges are complex, much effort has been expended in the development and testing of a suitable operating system for use by the central processor of the telephone exchanges. For example, for the AXE Group Switch a specialized operating system known as the APZ has been developed for coordinating practically all aspects of a telephone exchange. The operating system of the AXE Group Switch executes an APZ customized instruction set. Reflecting the complex nature of the group switch itself, the operating system is highly developed and intricate.
Some environments do not justify the capacity or cost of telephone exchange with a large group switch. For example, in rural or less populated regions, there are not a great number of subscribers for whom telephonic switching operations need to be performed. Furthermore, in some developing countries of the world, modest resources require that telephone switching be implemented on a smaller scale. However, these environments could someday have a potential need for greater switching capacity.
What is needed, therefore, is a telecommunications exchange which inexpensively implements simplified but potentially upgradable switching devices.